Download Climate Projections for Metro Vancouver

METHODOLOGY Climate Projections for Metro Vancouver Acknowledgements Metro Vancouver gratefully acknowledges the contribution of Pacific Climate Impacts Consortium, who conducted climate modelling, analysis, and data interpretation, and provided valuable suggestions for the report. Metro Vancouver thanks Pinna Sustainability for their assistance in writing the report. ii Climate Projections for Metro Vancouver REPORT Table of Contents Acknowledgements_________________________________________________________________________________________ii Executive Summary________________________________________________________________________________________ vi Introduction___________________________________________________________________________________________________ 1 Climate Scenario Selection______________________________________________________________________________ 2 Methodology_________________________________________________________________________________________________ 2 Climate Model Selection_________________________________________________________________________________ 3 Indicator Derivation________________________________________________________________________________________ 4 How to Read the Figures and Tables__________________________________________________________________ 4 A Note on Interpretation_________________________________________________________________________________ 5 General Climate Projections for Metro Vancouver ___________________________________________ 7 Warmer Temperatures____________________________________________________________________________________ 8 Wetter Winters, Drier Summers_______________________________________________________________________ 12 Precipitation Indicators_________________________________________________________________________________ 15 Snowpack __________________________________________________________________________________________________ 15 Dry Spells___________________________________________________________________________________________________ 18 Single-Day Maximum Precipitation _________________________________________________________________ 18 Five-Day Maximum Precipitation_____________________________________________________________________ 18 95th Percentile Wettest Days Precipitation________________________________________________________ 19 99th Percentile Wettest Days Precipitation________________________________________________________ 19 1-in-20 Wettest Day______________________________________________________________________________________ 20 Summer Temperature Indicators____________________________________________________________________ 22 Summer Days______________________________________________________________________________________________ 23 Tropical Nights____________________________________________________________________________________________ 24 Heat Days__________________________________________________________________________________________________ 24 Hottest day_________________________________________________________________________________________________ 24 1-in-20 Hottest day_______________________________________________________________________________________ 25 Growing Season Length _______________________________________________________________________________ 26 Growing Degree Days __________________________________________________________________________________ 27 Cooling Degree Days___________________________________________________________________________________ 29 Winter Temperature Indicators______________________________________________________________________ 31 Warmest Winter Day_____________________________________________________________________________________ 31 Coldest Night_____________________________________________________________________________________________ 31 1-in-20 Coldest Night___________________________________________________________________________________ 32 Frost Days _________________________________________________________________________________________________ 32 Ice Days ____________________________________________________________________________________________________ 34 Heating Degree Days ___________________________________________________________________________________ 34 Regional Impacts of Climate Change_____________________________________________________________ 35 Water Supply and Demand ___________________________________________________________________________ 36 Sewerage and Drainage________________________________________________________________________________ 37 Ecosystems_________________________________________________________________________________________________ 38 Agriculture_________________________________________________________________________________________________ 39 Air Quality and Human Health________________________________________________________________________ 40 Buildings and Energy Systems _______________________________________________________________________ 41 Transportation, Recreation, and Tourism___________________________________________________________ 41 Summary and Recommendations__________________________________________________________________ 42 Appendix 1: RCP4.5 and RCP2.6 Tables and Figures______________________________________ 43 Appendix 2: RCP8.5 Supplementary Maps_____________________________________________________ 55 Climate Projections for Metro Vancouver REPORT iii List of Tables Table 1: Average Daytime High Temperature__________________________________ 8 Table 2: Average Nighttime Low Temperature_________________________________ 8 Table 3: Total Precipitation over Seasons and Year ____________________________ 12 Table 4: Seasonal Snowpack Depth (Watershed Average)______________________ 16 Table 5: April 1 and May 1 Snowpack in the Watersheds________________________ 16 Table 6 : Annual Dry Spells_________________________________________________ 18 Table 7: Extreme Rainfall___________________________________________________ 19 Table 8: 1-in-20 Wettest Day________________________________________________ 20 Table 9: Hot Summers Indicators____________________________________________ 25 Table 10: Growing Season Length____________________________________________ 26 Table 11: Growing Degree Days_____________________________________________ 27 Table 12: Cooling Degree Days______________________________________________ 29 Table 13: Warmer Winter Days_______________________________________________ 32 Table 14: Frost Days________________________________________________________ 32 Table 15: Ice Days__________________________________________________________ 34 Table 16: Heating Degree Days______________________________________________ 34 List of Figures Figure 1: Winter Nighttime Low Temperature – Past____________________________________________ 9 Figure 2: Winter Nighttime Low Temperature – Future (2050s)_______________________________ 9 Figure 3: Monthly Daytime High Temperature – Past, 2050s, and 2080s__________________ 10 Figure 4: Monthly Nighttime Low Temperature – Past, 2050s, and 2080s________________ 11 Figure 5: Fall Precipitation – Past___________________________________________________________________ 13 Figure 6: Fall Precipitation – Future (2050s)______________________________________________________ 13 Figure 7: Monthly Total Precipitation – Past, 2050s, and 2080s______________________________ 14 Figure 8: April 1 Snowpack – Past _________________________________________________________________ 17 Figure 9: April 1 Snowpack – Future (2050s) _____________________________________________________ 17 Figure 10: 1-in-20 Wettest Day – Past_______________________________________________________________ 21 Figure 11: 1-in-20 Wettest Day – Future (2050s)__________________________________________________ 21 Figure 12: Summer Days – Future (2050s)__________________________________________________________ 23 Figure 13: Growing Degree Days – Past____________________________________________________________ 28 Figure 14: Growing Degree Days – Future (2050s)_______________________________________________ 28 Figure 15: Cooling Degree Days – Past_____________________________________________________________ 30 Figure 16: Cooling Degree Days – Future (2050s)________________________________________________ 30 Figure 17: Frost Days – Past___________________________________________________________________________ 33 Figure 18: Frost Days – Future (2050s)______________________________________________________________ 33 iv Climate Projections for Metro Vancouver REPORT List of Acronyms BCCAQBias Correction/Constructed Analogues with Quantile mapping reordering CMIP5 Coupled Model Intercomparison Project 5 ENSO El Niño-Southern Oscillation ETCCDI Expert Team on Climate Change Detection and Indices GHG Greenhouse Gas HVAC Heating, Ventilation and Air Conditioning IPCC Intergovernmental Panel on Climate Change PCIC Pacific Climate Impacts Consortium PDO Pacific Decadal Oscillation RCP Representative Concentration Pathway Climate Projections for Metro Vancouver REPORT v Executive Summary Temperatures in Metro Vancouver are warming. Global climate models project an average increase of about 3°C in our region by the 2050s. Metro Vancouver’s ability to adapt to climate change requires specific information on how changes in temperature and precipitation will play out locally, how expected changes may vary throughout the seasons, and about new climate extremes. Work has been completed by the Pacific Climate Impacts Consortium (PCIC) to understand the details of how our climate may change by the 2050s and 2080s. High-level changes for temperature and precipitation for the 2050s indicate that as our climate warms, our region can expect more than a doubling in the number of summer days above 25°C, from an average of 22 days per year to 55 days per year. The 1-in-20 hottest temperature (i.e., a temperature that has a 5% chance of occurring in any year) is projected to increase from 34°C to 38°C by the 2050s. This projected warming has implications for future energy supply, as heating demand for buildings will decrease by 29%, while cooling demand will increase to nearly 6 times what is currently required. This warming also translates into changes that are important to our ecosystems, including a 20% increase in the length of the growing season and a 45% increase in growing degree days. Warmer winters mean the region will experience a 60% decrease in the number of frost days, affecting ecosystems, infrastructure, and our economy. A modest 5% increase in annual precipitation is projected in our region by the 2050s, though indications of when that precipitation will occur are projected to change in important ways. October and vi Climate Projections for Metro Vancouver REPORT November are expected to see the greatest increase in precipitation, with precipitation expected to fall increasingly during extreme events. Approximately 30% more precipitation can be expected to fall on the 95th percentile wettest days, and approximately 60% more on the 99th percentile wettest days. The amount of rain falling in a 1-in-20 event could increase by 30% by the 2050s. Despite the projected increased intensity of wet events, the amount of rain in summer is expected to decrease by 20%, lengthening dry-spell duration by about 20%, from 21 consecutive days to 26 days. Most of the projected climate changes described in this report will be felt more or less uniformly throughout the region. Certain impacts, however, may differ substantially between low-lying areas where the majority of the population is situated, and high elevations such as the slopes of the North Shore. In particular, the wettest areas in the local mountains will become even wetter. However, with warmer temperatures and more precipitation falling as rain, the April 1 snowpack depth in the watersheds is projected to decrease almost 60% by the 2050s. The most dramatic regional differences are for frost days and growing-season length, where high elevations show about double the change of low elevations, because temperatures will rise above thresholds that were rarely experienced in the past. The projected changes to climate will have multiple impacts in our region. This report provides information to support our region to adapt to the changes ahead. Introduction Today, new information is available for producing high resolution regional climate projections. This report provides our region with an improved understanding of projected local climate change trends in temperature, precipitation, and related indices of extremes. While sea level rise is an important aspect of climate change with significant regional impacts, it is not addressed in this report as it does not require the same type of regional downscaling. This work offers information on multiple indicators that represent key properties of our climate system, which together tell a story of how our climate is expected to change over time. Cross-cutting themes emerge that demand attention from those charged with planning for the future. These include the provision of services to support safe human settlements, the health of our population, substantial shifts to our ecosystems, and the related economic impacts of those shifts. Information provided in this document is intended to describe a probable future and enable our region’s planners, engineers, and policy makers to make better-informed decisions on how to plan and adapt to changes ahead. This information could support development of design guidelines for future planning. In the following sections, you will find a broad, general description of our changing climate, followed by detailed descriptions of specific climate indicators. This is followed with a thematic discussion of potential impacts of climate change that we can expect to experience in our region in years to come. Climate Projections for Metro Vancouver REPORT 1 METHODOLOGY Methodology Climate Scenario Selection Various future trajectories of greenhouse gas (GHG) emissions are possible, and depend directly on global political initiatives and socio-economic changes that will occur over the coming years. This report presents the internationally recognized “business as usual” greenhouse gas emissions scenario, known as Representative Concentration Pathway 8.5 (RCP8.5). Additional information from lower emissions scenarios (RCPs 4.5 and 2.6) is available for sensitivity analysis and to illustrate the relationship between adaptation and greenhouse gas emissions reductions, or mitigation (see Appendix 1). Global average surface temperature change (°C) In general terms, RCP8.5 corresponds to “business as usual” GHG emissions for the remainder of the century. The RCP4.5 “medium stabilization” scenario represents mitigation efforts that result in about half of the emissions compared to the RCP8.5 scenario. Substantial and sustained reductions in GHG emissions—for example, extensive adoption of biofuels and vegetarianism, along with carbon capture and storage—would be required to achieve RCP2.6, which is the only pathway that would keep global warming below 2°C above pre-industrial temperatures. The projected global temperature change for each pathway is illustrated below. Representative Concentration Pathways (RCPs) RCPs describe potential 21st century scenarios of GHG emissions, atmospheric GHG concentrations, air pollutant emissions, and land use. These RCPs are used for making projections, and are based on the factors that drive anthropogenic GHG emissions: population size, economic activity, lifestyle, energy use, land use patterns, technology adoption, and climate policy. Each of the RCP emissions pathways is achievable, and directly relates to the choices made by global society. While recent commitments, including the 2015 COP21 Paris Agreement, correspond with RCP2.6, to date public policy continues to reflect the RCP8.5 pathway. It is prudent to plan for an RCP8.5 future until global mitigation actions begin to catch up with commitments. Mean over 2081-2100 Figure SPM.6(a) from IPCC’s Climate Change 2014: Synthesis Report shows modeled global average surface temperature change relative to 1986-2005. The mean of the projections (lines) and a measure of uncertainty (shading) are shown for RCP8.5 (red) and RCP2.6 (blue). The number of climate models used to calculate the mean is indicated. 2 Climate Projections for Metro Vancouver REPORT METHODOLOGY Climate Model Selection Many different, highly sophisticated models are used to simulate how the earth’s climate will respond to changes in greenhouse gas concentrations, each with different strengths and weaknesses. To manage the uncertainty associated with modelling, it is best practice to apply an ensemble approach that uses several models to describe the bounds of projected climate change. About Climate Models More information about climate models is available from the Pacific Institute for Climate Solutions’ Climate Insights 101 course. •Global climate models: http://pics.uvic.ca/ insights/module1_lesson4/player.html •Regional climate modelling and impacts in British Columbia: http://pics.uvic.ca/ education/climate-insights-101#quicktabsclimate_insights_101=1 The results in this report are based on a subset of climate models selected from the Coupled Model Intercomparison Project 5 (CMIP5). The CMIP5 climate models were first screened according to their ability to replicate historical data, and from them, the ensemble of 12 models was chosen to provide the widest range of projected change for a set of climate parameters. Information from the large-scale global climate models was translated into predictions at local scales using a procedure called downscaling. The model projections were downscaled to a 10 km grid by making use of a historical daily time series (ANUSPLIN) in conjunction with the climate model projections. BCCAQ statistical downscaling was used, which is a hybrid climate analogue/ quantile mapping method. Daily temperature and precipitation observations and future projections at 10 km resolution were then draped over an 800 m grid (PRISM) of 1971–2000 average temperature or precipitation to generate high-resolution maps. Climate Projections for Metro Vancouver REPORT 3 METHODOLOGY Indicator Derivation How to Read the Figures and Tables The historical baseline period used for all indicators in the report is 1971–2000. Values are averaged over this 30-year period to smooth out annual variability. The future projections are for the 2050s (which is an average of modelled values over the 2041–2070 period) and 2080s (2071–2100). The three RCP scenarios have somewhat similar greenhouse gas concentrations in the 2050s, but diverge considerably by the 2080s. Indicators of climate change take a similar divergent pattern by the 2080s. The following methods were used when developing the values shown in the tables, maps, and plots in this report: Many of the indicators of extreme events used in this report are derived using the definitions recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI), known as the CLIMDEX indices1. The indicator names used in this report have been translated into plain language, with the original CLIMDEX names provided in the tables for reference. Some indicators are defined by ETCCDI on a monthly basis only such as TXx (monthly maximum daytime high temperature). In some cases, we consider seasonal and annual versions of CLIMDEX indices by taking the corresponding maximum (or minimum) from the highest (or lowest) month in that season or year. Sea level rise, which does not require the same downscaling to examine regional impacts, was not included in this study. Projections of rising ocean levels are addressed by provincial guidelines.2 Some adaptation planning will require detailed assessments of sea level rise in combination with other local conditions such as subsidence and wave effects. 1 http://www.climdex.org/indices.htm http://www.env.gov.bc.ca/wsd/public_safety/flood/pdfs_word/ guidelines_for_mgr_coastal_flood_land_use-2012.pdf 2 4 Climate Projections for Metro Vancouver REPORT Values for each time period (past, 2050s, and 2080s) are averaged over each 30-year period. The 30year period used to calculate past values is 1971– 2000; the 2050s refer to 2041–2070, and the 2080s refer to 2071–2100. Seasons are presented as winter (DecemberJanuary-February), spring (March-April-May), summer (June-July-August), and fall (September-October-November). In tables throughout the document, projected change is given for the mean of the model ensemble along with the range (10th to 90th percentile) of the model ensemble. The 10th to 90th percentile range describes the uncertainty among the models and natural climate variability. Average or mean of model ensemble 10th percentile of model ensemble 90th percentile of model ensemble Past (°C) 2050s Change (°C) Average (Range) Winter 5 2.4 (1.3 to 3.0) Spring 12 2.9 (1.7 to 4.7) Values in tables are averaged over the entire region (within the regional boundary shown on the maps), unless labelled as low elevation or high elevation. In this report, lower-elevation values are averaged within the geographic boundaries of the City of Vancouver, while higher-elevation values are averaged within the boundaries of the District of North Vancouver. These municipalities were being analyzed for other studies, and were used to represent lower- and higher-elevation areas of the region. METHODOLOGY Maps show only the mean values of the model ensemble. Maps are provided in the body of the report when they add meaning to data interpretation, with additional maps for remaining indicators presented in Appendix 2. For the 1-in-20 events described in this report, the “5% chance of occurrence” is based on an average over each 30-year period. To be precise, since climate change will occur throughout that time, there is slightly less than a 5% chance of such an event occurring at the beginning of the period and more than 5% chance at the end of the period, with an average 5% chance over the period. This report provides several box-and-whisker plots to illustrate year-to-year and model-to-model variability over time. The diagram below illustrates how these plots are to be interpreted. Individual values with a distance from the median greater than 1.5 times the total height of the box (also called the interquartile range) 90th percentile 75th percentile Median, or 50th percentile of all monthly average values from the 12 models over the 30 year period. 25th percentile 10th percentile A Note on Interpretation This report tells the story of how we can expect temperature and precipitation to change in the Metro Vancouver region. When reviewing the data provided in the tables and figures below, it is important to note the following: For some indicators, values for specific geographic areas may be more appropriate than the regional averages presented in the tables. These values can be obtained by looking at the maps presented in the report body and in Appendix 2. The 10th to 90th percentile values projected by the ensemble are important for adaptation planning, as they take into account the range of uncertainty when projecting future climate change. Risk managers may find it appropriate to consider 90th percentile values when planning critical infrastructure investments. Climate Projections for Metro Vancouver REPORT 5 GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER 6 Climate Projections for Metro Vancouver REPORT GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER General Climate Projections for Metro Vancouver The Metro Vancouver region can expect changes to our climate in the coming years. At a broad level, this will mean: warmer temperatures, a decrease in snowpack, longer dry spells in summer months, more precipitation in fall, winter, and spring, and, more intense extreme events. These changes will not always happen consistently over the region or over time as seasonal and yearly variations will occur. For most variables, projected change appears somewhat different from the past by the 2050s, and by the 2080s, projections indicate substantial changes, resulting in a very different lived experience than the Metro Vancouver of today. This is particularly true for the temperature related variables. This section of the report presents general projections, and is followed by sections with more detailed climate indicators including indices of extremes for precipitation, summer temperatures and winter temperatures. Each section includes a definition of the indicator and a summary of projected values. Climate Projections for Metro Vancouver REPORT 7 GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER Warmer Temperatures ABOUT THESE INDICATORS Daytime high and nighttime low temperatures are averaged over each month, each season, or annually in the tables and plots below. PROJECTIONS All models project daytime high and nighttime low temperatures to rise. While temperature can be expected to increase year round, the greatest increases will occur in the summer months. By the 2050s, daytime high temperatures will be substantially warmer (an increase of 3.7°C) in summer. By the 2080s, we can expect summer daytime highs to increase by 6°C. Nighttime lows are also projected to rise by approximately 3°C in all seasons by the 2050s, resulting in an average winter low of 2°C, compared to an average winter low below zero in the past. The winter nighttime low can be expected to increase to 4°C by 2080s. Summer nighttime lows are also projected to increase dramatically, from 10°C in the past to 16°C by the 2080s. Maps indicate that warming can be expected uniformly throughout the region, with the warmest areas expected in the valleys and low-lying areas. In the future, only the tops of mountains will have temperatures below zero in the winter, on average. table 1: AVERAGE DAYTIME HIGH TEMPERATURE Past (°C) 2050s Change (°C) Average (Range) 2080s Change (°C) Average (Range) Winter 5 2.4 (1.3 to 3.0) 4.4 (2.8 to 5.7) Spring 12 2.9 (1.7 to 4.7) 4.7 (2.8 to 7.3) Summer 21 3.7 (2.4 to 5.2) 6.0 (3.7 to 8.4) Fall 13 2.8 (1.3 to 3.9) 4.5 (2.9 to 6.2) Annual 13 2.9 (1.6 to 4.2) 4.9 (3.0 to 6.6) table 2: AVERAGE NIGHTTIME LOW TEMPERATURE Past (°C) 2080s Change (°C) Average (Range) Average (Range) Winter -1 2.9 (1.8 to 3.5) 4.9 (3.6 to 5.7) Spring 3 2.9 (2.0 to 3.8) 4.6 (3.2 to 6.0) 10 3.2 (1.9 to 4.7) 5.2 (3.5 to 7.7) Fall 5 2.8 (1.7 to 4.0) 4.5 (3.1 to 6.0) Annual 4 2.9 (1.9 to 4.0) 4.8 (3.3 to 6.3) Summer 8 2050s Change (°C) Climate Projections for Metro Vancouver REPORT 49.049.2 49.449.649.8 LATITUDE (ºN) GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER -123.5 -122.5-122.0 LONGITUDE (ºN) 49.049.2 49.449.649.8 Figure 1: LATITUDE (ºN) -123.0 -123.5 WINTER NIGHTTIME LOW TEMPERATURE – PAST -123.0 -122.5-122.0 LONGITUDE (ºN) Figure 2: WINTER NIGHTTIME LOW TEMPERATURE – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 9 GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER Seasonal Variability in Temperature The box-and-whisker plots below of monthly high and low temperatures show that the new normal for the region may be very unlike the past. In these plots, the larger spread in future boxes could indicate that some years may be quite warm when others are not, or could mean there is more uncertainty in how the climate will respond to increasing atmospheric greenhouse gas concentrations. The daytime high temperature plot (Figure 3) shows that the median monthly average daytime high in the 2080s will be hotter than the 90th percentile of monthly averages in the past, notably in July, August, and September. In the 2080s, most September temperatures will be hotter than August temperatures would have been in the past. In the 2080s, average daytime highs in January will be similar to those of March in the past. Figure 3: MONTHLY DAYTIME HIGH TEMPERATURE – PAST, 2050s, AND 2080s Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. 10 Climate Projections for Metro Vancouver REPORT GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER In terms of nighttime lows (Figure 4), about 75% of past January average temperatures were below freezing for the region as a whole. By the 2050s, 90% of January and December average nighttime lows are expected to be above freezing. In past summers, cooler nighttime temperatures offered relief from hot days. By the 2050s, over 90% of monthly average nighttime lows are hotter than the hottest 10% in the past, for April through October. These projections indicate a future that has little in common with our current climate in terms of nighttime low temperatures. Figure 4: MONTHLY NIGHTTIME LOW TEMPERATURE — PAST, 2050s, AND 2080s Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. Climate Projections for Metro Vancouver REPORT 11 GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER Wetter Winters, Drier Summers ABOUT THIS INDICATOR PROJECTIONS Total precipitation is all precipitation summed over a month, season, or year, including rain and snow water equivalent. This is a high-level indicator of how precipitation patterns are projected to change. Projections indicate that our region will experience an increase in total annual precipitation of a modest 5% by the 2050s, and a more substantial increase of 11% by the 2080s. While these increases alone are not a dramatic departure from the past, the increase in precipitation will be distributed unevenly over the seasons. In our region, most rain falls over the winter months, and this will continue to occur in the future. The largest percentage increase in rainfall will occur in the fall season, increasing 11% by the 2050s and 20% by the 2080s. Winter and spring precipitation will both increase as well. Summer, already our region’s driest season, will experience a decline of 19% by the 2050s, and a decline of 29% by the 2080s. While the models indicate a range of possible change, they mostly agree about the direction of change for each season. table 3: TOTAL PRECIPITATION OVER SEASONS AND YEAR 12 Past (mm) 2050s (mm) 2080s (mm) Fall 580 642 Winter 683 Spring 2050s Percent Change (%) 2080s Percent Change (%) Average (Range) 693 11 (-1 to 24) 20 (10 to 38) 714 780 5 (-3 to 12) 14 (2 to 27) 400 430 447 8 (-4 to 15) 12 (3 to 25) Summer 206 168 147 -19 (-41 to 1) -29 Annual 1869 1953 2068 5 (-1 to 9) 11 Climate Projections for Metro Vancouver REPORT Average (Range) (-53 to -6) (2 to 17) GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER 49.049.2 49.449.649.8 LATITUDE (ºN) The maps below show the amount of precipitation that is projected to fall and indicates that the wetter areas are expected to experience the largest increases in precipitation. -123.5 -123.0 -122.5 -122.0 LONGITUDE (ºN) 49.049.2 49.449.649.8 LATITUDE (ºN) Figure 5: FALL PRECIPITATION – PAST -123.5 -123.0 -122.5 -122.0 LONGITUDE (ºN) Figure 6: FALL PRECIPITATION – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 13 GENERAL CLIMATE PROJECTIONS FOR METRO VANCOUVER Seasonal Variability in Precipitation When examining monthly precipitation values in the plot below (Figure 7), we see that increases in precipitation amounts within a season are not uniform across months. For example, the fall months show a divergent pattern: September shows a reduction in precipitation, while October and November show the largest increases in precipitation. December and January show the largest increases in winter precipitation. The plot also indicates the potential for much drier summer months than we have ever experienced. September is projected to get drier over time, extending the dry season into the fall. The models illustrate that we can expect more precipitation in the already wet seasons, less precipitation in already dry summers, and considerably more rain falling in some years, while other years will experience droughts. In southwestern BC, year-to-year precipitation variability is regulated by two global climate patterns: the Pacific Decadal Oscillation (PDO) and the El Niño-Southern Oscillation (ENSO). PDO has varied between warm and cool phases a few times over the last century. ENSO varies between three phases: neutral years, El Niño events that typically mean a warmer and drier winter and spring, and La Niña events that are cooler and wetter. The magnitude of the natural variability of PDO and ENSO cycles is comparable to the projected changes due to climate change in some cases.The effects of ENSO and PDO tend to cancel out in the projections shown in the tables and maps of this report, since those values are averaged over 30 years. In the future, the decadal and year-to-year variability of the PDO and ENSO patterns will be felt on top of the “new normal” reflected by the future projections. The ranges in the box-and-whisker plot below illustrate year-to-year variability including contributions from ENSO within each 30-year period. Figure 7: MONTHLY TOTAL PRECIPITATION – PAST, 2050s, AND 2080s Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. 14 Climate Projections for Metro Vancouver REPORT Precipitation Indicators Metro Vancouver’s drinking water comes from three mountain reservoirs supplied by rainfall and snowmelt in the watersheds. Changes in precipitation patterns will have impacts on water supply. Drainage and stormwater infrastructure in the region is designed to withstand extreme weather events. As the climate warms, more moisture is held in the atmosphere and released during precipitation events, resulting in more intense future storm events. New thresholds for extreme weather events will challenge regional infrastructure, such as sewage and drainage systems. Snowpack ABOUT THIS INDICATOR PROJECTIONS Snowpack refers to the depth of snow on the ground, either daily depths averaged over a season, or in the case of the April 1 and May 1 snowpack, the snow depth on that specific date. This indicator is measured within the boundaries of the three watersheds that supply the majority of Metro Vancouver’s drinking water. In this context, the snowpack indicator provides a measure to assist in determining how much snowmelt will be available in the watersheds to flow into our region’s reservoirs. Snowpack is projected to decrease significantly over time. Our region’s snowpack is typically highest in the spring months, after snow has accumulated over the winter and early spring, with past spring snowpack depth measuring 266 cm. In the winter months, projections indicate a 56% decrease in snowpack by the 2050s, resulting in much lower spring and summer snow levels. This trend is expected to magnify by the 2080s with a 77% decrease in winter snowpack and 84% decrease in spring snowpack, averaged across the three watersheds. Climate Projections for Metro Vancouver REPORT 15 PRECIPITATION INDICATORS table 4: SEASONAL SNOWPACK DEPTH (WATERSHED AVERAGE) Past (cm) 2050s (cm) 2080s (cm) 2050s Percent Change (%) 2080s Percent Change (%) Average (Range) Average (Range) Winter 208 93 49 -56 (-63 to -45) -77 (-86 to -59) Spring 266 102 43 -62 (-72 to -51) -84 (-94 to -67) Summer 73 11 3 -86 (-94 to -80) -97 (-99 to -92) Fall 37 10 5 -75 (-82 to -65) -87 (-94 to -77) Looking more closely at spring snowpack in the watersheds, the April 1 snow depth will decrease by 58% by the 2050s, from 292 cm to 123 cm, and by 82% by the 2080s, to 56 cm. The May 1 snow depth will diminish even more—a decrease of 66% by the 2050s, and 87% by the 2080s. The following table shows the changes for each of Metro Vancouver’s three watersheds (Capilano, Seymour, and Coquitlam). The boundaries of these watersheds are illustrated on the maps below. May 1 April 1 table 5: APRIL 1 AND MAY 1 SNOWPACK IN THE WATERSHEDS 2050s Percent Change (%) Past (cm) 2050s (cm) 2080s (cm) Watersheds average 292 123 56 -58 Capilano 256 105 45 Seymour 274 115 Coquitlam 336 Watersheds average Average (Range) 2080s Percent Change (%) Average (Range) (-71 to -46) -82 (-94 to -61) -59 (-73 to -47) -83 (-95 to -64) 47 -59 (-73 to -46) -84 (-96 to -63) 144 71 -57 (-70 to -44) -80 (-92 to -57) 264 93 37 -66 (-78 to -54) -87 (-96 to -73) Capilano 229 77 29 -67 (-80 to -56) -88 (-97 to -76) Seymour 244 81 28 -67 (-81 to -56) -89 (-98 to -76) Coquitlam 308 114 51 -64 (-76 to -52) -84 (-94 to -69) The maps below illustrate the snowline moving up the mountains as the spring snowpack diminishes into the future. The values presented in the tables above are calculated within the boundaries of the watersheds shown on the maps. Note that the white areas on the map represent areas where snowpack is nearly permanent, i.e., at or near glaciers. The snowpack model does not apply in these locations. Snow depths in these locations are omitted from the calculation of values in the tables above. However, the area of permanent snow (glaciers) are shown to decrease over time. 16 Climate Projections for Metro Vancouver REPORT LATITUDE (ºN) LATITUDE (ºN) 49.0 49.049.2 49.4 49.649.8 PRECIPITATION INDICATORS -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) 49.2 49.4 49.649.8 Figure 8: APRIL 1 SNOWPACK – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) Figure 9: APRIL 1 SNOWPACK – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 17 PRECIPITATION INDICATORS Dry Spells ABOUT THIS INDICATOR PROJECTIONS Dry spells is a measure of the number of consecutive days where daily precipitation is less than 1 mm. The value denotes the longest stretch of dry days in a year, typically in summer. This indicator reflects times of the year when reservoirs are not recharged by rainfall. This number does not indicate extreme droughts, as it is averaged over the 30-year period. The past average longest period of consecutive days without rain (under 1 mm) in our region is 21 days. Dry spells on average are expected to increase to 26 days by the 2050s, and 29 days by the 2080s. table 6: ANNUAL DRY SPELLS CLIMDEX index: CDD Dry Spell duration Past (days) 2050s (days) 2080s (days) 21 26 29 2050s Percent Change (%) 2080s Percent Change (%) Average (Range) Average (Range) 22 (3 to 40) 37 (16 to 65) Single-Day Maximum Precipitation ABOUT THIS INDICATOR PROJECTIONS Single-day maximum precipitation describes the largest amount of rain that falls on any single day in the year. This value is used to understand how extreme precipitation will change over time. As noted previously in the General Climate Projections section, a modest increase (5%) in total annual precipitation is expected by the 2050s. Models project that the increase will be concentrated into the wettest days. The wettest single day of the year will see 17% more rain by the 2050s, and 32% more by the 2080s. Five-Day Maximum Precipitation ABOUT THIS INDICATOR PROJECTIONS Five-day maximum precipitation describes the largest amount of rain that falls over a period of 5 consecutive days in the year. Again, as noted earlier, a modest increase (5%) in total annual precipitation is expected by the 2050s, with models projecting the increase will be concentrated into the wettest days. The amount of rain in the wettest 5-day period will increase by 12% by the 2050s, and 25% by the 2080s. 18 Climate Projections for Metro Vancouver REPORT PRECIPITATION INDICATORS 95th Percentile Wettest Days Precipitation ABOUT THIS INDICATOR PROJECTIONS The 95th percentile wettest days precipitation indicator points to the total amount of rain that falls on the wettest days of the year, specifically on days when precipitation exceeds a threshold set by the annual 95th percentile of wet days during the baseline period (1971–2000). This measure indicates how much total annual precipitation falls during these heavy events, which is a combination of both how often these events occur that exceed the 95th percentile threshold amount, and the size of these events. The wettest periods in our region are projected to become wetter. The wettest days that exceed the baseline 95th percentile threshold will produce 32% more rain by the 2050s, and 62% more rain by the 2080s. 99th Percentile Wettest Days Precipitation ABOUT THIS INDICATOR PROJECTIONS The 99th percentile wettest days precipitation indicator points to the total amount of rain that falls on the wettest days of the year, specifically on days when precipitation exceeds a threshold set by the annual 99th percentile of wet days during the baseline period (1971–2000). This measure indicates how much total annual precipitation falls during these heavy events, which is a combination of both how often these events occur that exceed the 99th percentile threshold amount, and the size of these events. The 99th percentile wettest days that exceed the baseline 99th percentile threshold are projected to produce 61% more rain by the 2050s, and 127% more rain by the 2080s than in the past. These projected large increases mean that we can expect more frequent and more intense storms in the future. table 7: EXTREME RAINFALL CLIMDEX index Past (mm) 2050s Percent Change (%) 2080s Percent Change (%) Average (Range) Average (Range) Single-day maximum precipitation Rx1day 69 17 (6 to 31) 32 (16 to 43) Five-day maximum precipitation Rx5day 159 12 (4 to 20) 25 (13 to 35) 95th percentile wettest days precipitation R95pTOT 398 32 (6 to 58) 62 (37 to 89) 99th percentile wettest days precipitation R99pTOT 122 61 (24 to 119) 127 (79 to 200) Climate Projections for Metro Vancouver REPORT 19 PRECIPITATION INDICATORS 1-in-20 Wettest Day ABOUT THIS INDICATOR PROJECTIONS The 1-in-20 wettest day is the day so wet that it has only a one-in-twenty chance of occurring in a given year. That is, there is a 5% chance in any year that a one-day rainfall event of this magnitude will occur. This indicator points to what we can expect in terms of extreme one-day precipitation events in our region. Significantly more precipitation is expected to fall during the 1-in-20 (or 5% chance) wettest day extreme storm events in the future. Larger 1-in-20 wettest day events could mean up to 36% more rain in low-lying areas by the 2050s, and 59% by the 2080s. In the past, on average, 154 mm of precipitation fell during the entire month of January—by the 2080s, there will be a 5% chance that this amount of rain could fall in a one-day event. In addition to more precipitation during future 1-in20 events, these findings also indicate that what was previously characterized as a 1-in-20 event will happen more often. table 8: 1-IN-20 WETTEST DAY Past (mm) 2050s Change (mm) Average 2080s Change (mm) (Range) Average (Range) Region 105 30 (7 to 43) 46 (24 to 70) Low elevations 89 31 (8 to 50) 51 (30 to 86) High elevations 121 23 (7 to 38) 38 (16 to 60) The maps below indicate that the greatest change in 1-in-20 wettest day rainfall will occur where heavy rain already falls. The biggest changes are in the mountains between Coquitlam Lake and Pitt Lake, and other high points to the east of the region. 20 Climate Projections for Metro Vancouver REPORT 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) PRECIPITATION INDICATORS -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE 10: 1-IN-20 WETTEST DAY – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE 11: 1 -IN-20 WETTEST DAY – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 21 Summer Temperature Indicators The downscaled outputs from the climate models project increases in average summer (June-JulyAugust) daytime high temperatures that suggest Vancouver would be warmer than present-day San Diego by the 2050s, and even warmer by the 2080s. While warmer temperatures may have benefits and be welcomed in some ways, they will also need careful consideration when planning for a growing population in the region 22 Climate Projections for Metro Vancouver REPORT Descriptions of these indicators are offered below, and values for these projections are given in Table 9: Hot Summers Indicators. SUMMER TEMPERATURE INDICATORS Summer Days ABOUT THIS INDICATOR PROJECTIONS Summer days tells us how many days reach temperatures over 25°C in any one year. This measure indicates how often we can expect “summer weather” to occur in the future. In the past, our region experienced 22 summer days a year, and we can expect significantly more summer days in the future. Models project more than double the number of summer days by the 2050s, and more than triple by the 2080s. This means that future summers may have 55 days above 25°C by the 2050s, and 79 days by the 2080s. 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) The maps for summer days included below show that the number of hot days will be highest in the eastern reaches of the Fraser Valley, though the greatest change will be in Metro Vancouver, where the number of summer days was lower in the past. -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE 12: SUMMER DAYS – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 23 SUMMER TEMPERATURE INDICATORS Tropical Nights ABOUT THIS INDICATOR Tropical nights refers to the number of days in a year when the nighttime low temperature is greater than 20°C. This measure is important when designing cooling systems for buildings, as nighttime temperatures will not aid in indoor cooling on these nights. PROJECTIONS In the past, our region experienced no nighttime lows warmer than 20°C, or tropical nights, on average. By the 2050s, it is expected that lower elevations in our region may experience 4 tropical nights a year (projections range from 0 to 10 nights, depending on the model), and by the 2080s, that number will increase to 19 (range of 2 to 48 nights). Heat Days Hottest day ABOUT THIS INDICATOR ABOUT THIS INDICATOR Heat days refers to the number of days where the daytime temperature exceeds 30°C. This indicator is useful to show “heat zones” for plants, because some plants experience physiological stress at temperatures above 30°C. Hottest day refers to the highest daytime high temperature of the year, usually experienced during the summer months. The annual high for each year is an indicator of extreme temperatures and is averaged over a 30-year period here. PROJECTIONS PROJECTIONS In the past, our region experienced 2 heat days per year, or days with temperature above 30°C, on average. By the 2050s, we can expect 14 heat days per year. This is projected to increase to 29 heat days per year by the 2080s. The past hottest day temperature was 31°C for the region. This will increase to about 35°C by the 2050s, and to 37°C by 2080s. Like summer days (shown in Figure 10) the highest increases can be expected in our region’s valleys and in locations further from the ocean. 24 Climate Projections for Metro Vancouver REPORT SUMMER TEMPERATURE INDICATORS 1-in-20 Hottest day ABOUT THIS INDICATOR PROJECTIONS 1-in-20 hottest day refers to a day so hot that it has only a one-in-twenty chance of occurring in a given year. That is, there is a 5% chance in any year that temperatures could reach this magnitude. This indicator points to what we can expect in terms of extreme temperature highs in our region. As temperatures increase, so will extreme heat events. Our past 1-in-20 hottest day temperature is 34°C. By the 2050s we can expect this value to increase to 39°C, and to 41°C by the 2080s. The range in models suggests that temperatures may even rise to 43°C by the 2080s. This is a significant departure from what the region is accustomed to experiencing. The 1-in-20 hottest day temperatures will affect the entire region, and like other hot summer indicators, will most affect our region’s valleys and other areas furthest from the cooling effect of the ocean. table 9: HOT SUMMERS INDICATORS CLIMDEX index Past Summer days (# of days >25°C) SU 22 55 Tropical nights (# of nights >20°C) TR 0 Heat days (# of days >30°C) Hottest day (°C) 1-in-20 hottest day (°C) 1-yr TXx 2050s 2080s 2050s Change 2080s Change Average (Range) Average (Range) 79 33 (20 to 46) 57 (34 to 80) 2 11 2 (20 to 46) 11 (1 to 30) 2 14 29 12 (0 to 5) 27 (14 to 46) 31 35 37 3.9 (5 to 18) 6.4 (4.4 to 8.5) 34 39 41 4.6 (2.5 to 4.8) 6.9 (4.2 to 9.1) Climate Projections for Metro Vancouver REPORT 25 SUMMER TEMPERATURE INDICATORS Growing Season Length ABOUT THIS INDICATOR PROJECTIONS Growing season length is an annual measure that counts the number of days between the first span of at least 6 days with a daily average temperature greater than 5°C, and first span after July 1 of 6 days with a temperature less than 5°C. It indicates the length of the growing season for typical plants or crops in our region. In the past, our region had an average of 252 days in the growing season. In lower elevations 45 days will be added to the growing season by the 2050s, and 56 days by the 2080s, resulting in nearly a year-round growing season of 357 days on average. In forest ecosystems at higher elevations, the growing season will lengthen by more days as higher temperatures creep up the mountains and more days tip over the 5°C threshold. By the 2080s, we will see a growingseason length of 325 days at higher elevations, which is more than we saw in the past at lower elevations. table 10: GROWING SEASON LENGTH CLIMDEX index: GSL 26 Past (days) 2050s (days) 2080s (days) 2050s Change (days) 2080s Change (days) Average (Range) Average (Range) Region 252 304 331 52 (38 to 62) 79 (66 to 87) Low elev. 301 346 357 45 (39 to 52) 56 (50 to 62) High elev. 217 281 325 64 (43 to 82) 108 (90 to 123) Climate Projections for Metro Vancouver REPORT SUMMER TEMPERATURE INDICATORS Growing Degree Days ABOUT THIS INDICATOR Growing degree days are a measure of heat accumulation that is useful for agriculture and horticulture. Growing degree days calculated here by how warm daily temperatures are compared to a base temperature of 5°C (although different base temperatures may be useful for different crops). For example, if a day had an average temperature of 11°C, that day would have a value of 6 growing degree days. Annual growing degree days are accumulated this way for each day of the year and then summed. This measure is a useful indicator of opportunities for agriculture, as well as the potential for invasive species to thrive. PROJECTIONS In the past, there were 1738 growing degree days in our region. Projections indicate increases in growing degree days throughout the region. By the 2050s, we can expect 47% more growing degree days, and 82% more growing degree days by the 2080s. The lower elevations will experience a larger absolute change in growing degree days, while mountain areas show a larger percentage change. table 11: GROWING DEGREE DAYS Past (degree days) 2050s 2080s (degree (degree days) days) 2050s Change (degree days) Average 2080s Change (degree days) (Range) Average (Range) Region 1738 2532 3157 824 (462 to 1182) 1419 (883 to 1922) Low elev. 2122 3051 3689 929 (548 to 1300) 1567 (1002 to 2096) High elev. 1467 2228 2801 761 (411 to 1114) 1334 (814 to 1829) Climate Projections for Metro Vancouver REPORT 27 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) SUMMER TEMPERATURE INDICATORS -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE 13: GROWING DEGREE DAYS – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE 14: GROWING DEGREE DAYS PAST– FUTURE (2050s) 28 Climate Projections for Metro Vancouver REPORT SUMMER TEMPERATURE INDICATORS Cooling Degree Days ABOUT THIS INDICATOR PROJECTIONS Cooling degree days is a measure of how hot it gets and for how many days. More specifically, it is a total of the number of degrees above 18°C that occur daily, summed over each day of the year, and provides an indication of when cooling might be required in buildings. Cooling degree days are useful indicators of energy demands for mechanical cooling. This information is important when planning heating, ventilation, and air conditioning (HVAC) systems, building design, energy systems, and related infrastructure. Historically there has been very little cooling demand in our region. This is reflected in the baseline average of 49 cooling degree days in the past. It is projected that there will be a 380% increase in cooling degree days by the 2050s, and a 784% increase by the 2080s. The large relative increases are partly the result of the fact that the historical baselines are so small. These increases represent a considerable departure from the past. Areas of lower elevation, where most buildings are located, will have more cooling demand than present-day Kamloops by the 2050s, and a higher cooling demand than present-day San Diego by the 2080s. table 12: COOLING DEGREE DAYS Past (degree days) 2050s 2080s (degree (degree days) days) 2050s Change (degree days) Average (Range) 2080s Change (degree days) Average (Range) Region 49 235 433 186 (81 to 295) 385 (184 to 606) Low elev. 58 300 535 242 (106 to 374) 477 (243 to 742) High elev. 36 177 346 141 (58 to 229) 310 (137 to 496) Climate Projections for Metro Vancouver REPORT 29 SUMMER TEMPERATURE INDICATORS 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) The maps below indicate that warmer areas are getting warmer, particularly on south facing slopes and furthest from the ocean. -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE 15: COOLING DEGREE DAYS – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE 16: COOLING DEGREE DAYS – FUTURE (2050s) 30 Climate Projections for Metro Vancouver REPORT METHODOLOGY Winter Temperature Indicators Future climate projections suggest our region will see warmer winter months. These indicators provide insight into the “new normal” for winter temperature in our region. Warmest Winter Day ABOUT THIS INDICATOR PROJECTIONS Warmest winter day is the highest temperature recorded during the winter months, in an average year. When considered in combination with the coldest night, this indicator is useful to describe the projected “new normal” for winters in our region. By the 2050s, we can expect to see the warmest winter temperature rise from 12°C to about 15°C. This value may increase to about 18°C by the 2080s. Coldest Night ABOUT THIS INDICATOR PROJECTIONS Coldest night refers to the lowest temperature of the year, in an average year, usually experienced at nighttime during the winter months. This indicator points to the lowest threshold of winter temperatures, and when considered along with the warmest winter day, helps describe the projected “new normal” for winters in our region. In the past, the coldest night had a temperature of -13°C. Models project annual lows to increase by roughly 5°C by the 2050s, to -8°C, and by 8°C by the 2080s, to -5°C. Climate Projections for Metro Vancouver REPORT 31 WINTER TEMPERATURE INDICATORS 1-in-20 Coldest Night ABOUT THIS INDICATOR PROJECTIONS 1-in-20 coldest night refers to a nighttime low temperature so cold that it has only a one-in-twenty chance of occurring in a given year. That is, there is a 5% chance in any year that a minimum temperature of this value will occur. This indicator is a marker of extreme winter cold temperatures. The 1-in-20 coldest night across the region will increase by 5°C by the 2050s to -15°C, and 8°C by the 2080s to 12°C. The winter nighttime low (-13°C) that in the past occurred roughly once per year will, by the end of the century, be experienced roughly once every 20 years. table 13: WARMER WINTER DAYS Climdex index Past (ºC) 2050s (ºC) 2080s (ºC) Warmest winter day TXx 12 15 Coldest winter night TNn -13 -20 1-in-20 coldest nighttime low 2050s Change (ºC) 2080s Change (ºC) Average (Range) Average (Range) 18 2.8 (0.6 to 4.0) 5.7 (2.0 to 10.1) -8 -5 5.1 (3.5 to 6.6) 8.1 (6.6 to 9.6) -15 -12 4.9 (3.0 to 7.5) 8.0 (4.7 to 10.4) Frost Days ABOUT THIS INDICATOR PROJECTIONS Frost days is an annual count of days when the daily minimum temperature is less than 0°C, which may result in frost on the ground. This indicator is useful when predicting how pests and invasive species may thrive in our shifting ecosystems. In the past, Metro Vancouver had 79 frost days a year. Lower elevations experienced only 39 frost days, while higher elevations had 92 frost days. Future projections indicate conditions where the “new normal” is a climate that is almost entirely frost-free in lower elevations. The region may expect 33 frost days by the 2050s, and 17 by the 2080s. The maps below illustrate that the loss of frost days will be most dramatic at higher elevations. table 14: FROST DAYS CLIMDEX index: FD 32 2050s Change (days) 2080s Change (days) Past (days) 2050s (days) 2080s (days) Region 79 33 17 -47 (-54 to -37) -63 (-68 to -52) Low elev. 39 11 4 -28 (-33 to -23) -35 (-38 to -30) High elev. 92 34 16 -58 (-68 to -46) -76 (-83 to -63) Climate Projections for Metro Vancouver REPORT Average (Range) Average (Range) 49.0 49.0 49.2 LATITUDE (ºN) LATITUDE (ºN) 49.4 49.649.8 WINTER TEMPERATURE INDICATORS -123.5 -123.0 FIGURE 17: FROST DAYS – PAST -122.5-122.0 LONGITUDE (ºN) 49.2 49.4 49.649.8 -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE 18: FROST DAYS – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 33 WINTER TEMPERATURE INDICATORS Ice Days ABOUT THIS INDICATOR PROJECTIONS Ice days is an annual count of days when the daily maximum temperature is less than 0°C. This indicator is useful when predicting snow formation and retention. In the past, Metro Vancouver had 12 ice days per year, mainly in areas of higher elevation. Future projections indicate a “new normal” where higher elevation areas experience very few days when the daily high temperature remains below freezing. The region may expect 4 ice days by the 2050s, and 2 by the 2080s. table 15: ICE DAYS CLIMDEX index: ID Past (days) 2050s (days) 2080s (days) Region 12 4 Low elev. 4 High elev. 13 2050s Change (days) 2080s Change (degree days) Average (Range) Average (Range) 2 -8 (-10 to -5) -11 (-12 to -8) 2 1 -3 (-3 to -1) -3 (-4 to -3) 4 2 -9 (-11 to -5) -11 (-13 to -9) Heating Degree Days ABOUT THIS INDICATOR PROJECTIONS Heating degree days is a measure of how cold it gets and for how many days. When the temperature is below 18°C, indoor heating is likely required to compensate for cold outdoor temperatures, and the further below this threshold, the more heat is required. In specific terms, it is a total of the number of degrees below 18°C that occur daily, summed for each day of the year. The lower the number of heating degree days, the less energy is required for heating buildings. Metro Vancouver experiences many heating degree days compared to cooling degree days. Our past regional annual average of heating degree days is 3489. Heating degree days are projected to decrease by 25% by 2050s, and by 40% by the 2080s table 16: HEATING DEGREE DAYS Past (degree days) 2050s 2080s (degree (degree days) days) Average (Range) 2080s Change (degree days) Average (Range) Region 3489 2605 2112 -884 (-1170 to -560) -1377 (-1751 to -964) Low elev. 2865 2045 1605 -820 (-1068 to -535) -1260 (-1606 to -891) High elev. 3834 2907 2383 -927 -1451 (-1858 to -1015) 34 2050s Change (degree days) Climate Projections for Metro Vancouver REPORT (-1241 to -583) Regional Impacts of Climate Change The projected changes to our climate discussed in this report will have multiple impacts in our region. This report provides information about the future climate that needs to be considered by planners in these areas: water supply and demand, sewage and drainage, ecosystems and agriculture, air quality and human health, buildings and energy systems, and, transportation, recreation, and tourism. The information in this report is particularity pertinent to those involved in providing adequate infrastructure to support safe human settlements, those concerned with the health of our population and ecosystems, and those anticipating economic impacts of our changing climate. Climate Projections for Metro Vancouver REPORT 35 REGIONAL IMPACTS OF CLIMATE CHANGE Water Supply and Demand The majority of the region’s drinking water comes from mountain reservoirs fed by rainfall and snowmelt. An increase in daytime high and nighttime low temperatures will cause more precipitation to fall as rain in the winter months. Rather than winter precipitation falling as snow to build a strong snowpack, winter rains and warmer temperatures will erode the winter snowpack and have a negative effect on the depth and duration of the snowpack into the spring and summer months. Monthly precipitation projections also indicate drier summers that could extend later into the year. At current levels of water use in our region, warmer annual temperatures and longer dry spells over the summer months, combined with reductions in snowpack, could put strain on the existing water supply during times of the year when temperatures are high and water is in greatest demand. Despite water conservation efforts, water demand is anticipated to increase to meet the needs of a growing population. Warmer summer temperatures and extended droughts could intensify these trends, potentially leading to increased water demand for outdoor water use and recreational activities. Increases in the magnitude of extreme rainfall events may increase the possibility of landslides in our region’s mountain areas, which could introduce additional turbidity into drinking water reservoirs. 36 Climate Projections for Metro Vancouver REPORT Sewerage and Drainage The extreme rainfall indicators illustrate future extreme events may be beyond the frequency and intensity of events for which we are currently prepared. If they were to be managed by our current infrastructure, we could expect periods of flooding, damage to property, and risks to human health. Extreme precipitation events may also affect slope stability, increase erosion and risk of landslides, and cause flooding in low-lying areas. This may cause damage to personal property and public infrastructure, and could compromise the health of streams, rivers, parklands, and their inhabitants. Increases in storm intensity will put significant pressure on our region’s sewerage and drainage systems. During intense rainfall events, storm sewers and urban streams can overflow and cause overland flooding. In addition, some areas of the region still have combined sewers that carry both sewage and stormwater in a single pipe. During heavy rainfall, combined sewers can fill up with more water than they can handle, and discharge directly into the nearest body of water. Wastewater treatment plants that are largely served by combined sewers will experience periods of higher inflows, which result in diminished treatment efficiency, more frequently. While this report did not calculate future 1-in-50 year (2% probability of exceedance) and 1-in-100 year (1% probability of exceedance) events, we can expect even larger relative changes in those events compared to the changes in the 1-in-20 (5% probability of exceedance) events projected in this study. It can also be assumed that trends related to extreme events and their relative intensity will continue past the end-of-century timeframe presented in this report. This information offers important context for those who design stormwater and other critical infrastructure in our region, and merits further detailed study to inform future design criteria, especially for infrastructure that is expected to last for many decades. Climate Projections for Metro Vancouver REPORT 37 REGIONAL IMPACTS OF CLIMATE CHANGE Ecosystems Temperature increases and changes in precipitation over the seasons will affect our regional ecosystems, including mountain and urban forests, parklands, and wetlands. As our climate shifts, the plants, trees, and pests that thrive here will also change. While some species will thrive, others will decline, and aspects of our local ecosystems will change significantly. The decrease in snowpack, frost days, and summer precipitation, combined with increasing temperatures, will cause stress to some forests that may cause tree growth to decline and mortality rates in vulnerable species to rise. Certain tree species in the region’s mountains may migrate to different elevations in search of suitable temperature and precipitation conditions. Pests, such as forest insects, that are currently managed by cold temperatures may experience outbreaks. Also, invasive species may be better able to thrive in changing conditions and may out-compete native species. Additionally, 38 Climate Projections for Metro Vancouver REPORT with the reduction of precipitation over the increasingly warm summer months, we can expect an increase in wildfire risk, which could dramatically affect the forest structure. Prolonged dry spells, stressed reservoirs, and warmer summer temperatures will also reduce soil moisture in the summer, which, coupled with limited supplemental watering, could result in widespread decline in urban tree growth and increased tree mortality. Longer drought periods, coupled with more intense precipitation at other times, will cause stress to plants, animals, and wetlands, will have an impact on soil chemistry and the soil’s capacity to retain water, and will contribute to the frequency and severity of flooding. Hotter summers with less precipitation will have a negative impact on terrestrial and aquatic species. For terrestrial species, decreased plant growth, heat stress, and scarcity of water reduce the quality of forage crops, causing increased competition for resources. Decreasing streamflow, warmer water temperatures, and an earlier freshet will cause stress to many aquatic species. Agriculture Changes in temperature and precipitation over the coming decades will have many positive and negative impacts on agriculture. Increasing temperatures can lead to higher crop productivity and a greater range of crops. Agricultural producers will feel a shift in costs, as energy for heating greenhouses will decrease in cooler months, and cooling needs for greenhouses and livestock facilities will increase during the summer season. As high temperatures become more variable with an increasing frequency of extreme events, plants may suffer from heat stress and sun scald, and the demand for heat-tolerant plants will increase. Increasing spring precipitation, and increases in extreme precipitation will also increase the potential for waterlogged soils, flooding, inadequate soil drainage, soil compaction, and leaching of nutrients from farmland. Longer summer drought conditions, combined with extreme rain, will stress soil structure, necessitating additional soil conditioning and supplementary irrigation. More growing degree days and a reduction of frost days will create a longer growing season in our region. Agricultural producers will be able to take advantage of new opportunities to grow different, and perhaps more valuable, crops, and can expect earlier harvests, and potentially year-round productive growing. This benefit will be coupled with increased pests and plant diseases, which can threaten plant health and crop productivity. Additionally, variations in temperature and precipitation may cause pollinators to emerge at inappropriate times and be unable to serve their vital role. Climate Projections for Metro Vancouver REPORT 39 REGIONAL IMPACTS OF CLIMATE CHANGE Air Quality and Human Health Temperature and precipitation have a direct relationship with air quality and human health in our region. As noted above, hotter, drier summer conditions, combined with decreased snowpack, may lead to an increase in wildfire activity within the region and in other areas that can bring smoke to the region from considerable distances. Air quality is impacted by wildfires, which contribute a significant amount of particulate matter into our air, causing an increase in adverse health impacts and visual haze. Particulate matter from wildfires is a known human carcinogen, and may become a greater health concern as temperatures rise. Air quality will suffer as concentrations of groundlevel ozone, a critical component of haze or smog, increase with temperature. Ozone is not directly emitted from human activities, but rather forms when other pollutants (nitrogen oxides and volatile organic compounds) react in sunlight on warm days. Levels of ozone tend to be elevated during midday on hot summer days, as the reaction accelerates above 25°C. People with lung disease, children, older 40 Climate Projections for Metro Vancouver REPORT adults, and people who are active outdoors may be particularly sensitive to future elevated ozone levels. Hotter, drier summers will also cause heat stress and have an impact on human health. Although heat stress may appear less threatening on the coast than in areas that already experience hot summers, stress levels remain high because much of the population is more accustomed to mild temperatures and is not prepared to accommodate high temperatures. Non-respiratory emergency room visits in Vancouver currently increase with high summer temperatures, and are expected to increase further with an aging population. Warmer winters will result in less use of fireplaces and wood stoves for heating, thereby improving winter air quality in urban areas and reducing human exposure to smoke from wood-burning appliances. Wood smoke contains particulate matter that has been linked to lung disease and heart disease, and is carcinogenic to humans when inhaled. REGIONAL IMPACTS OF CLIMATE CHANGE Buildings and Energy Systems Substantial shifts in energy demand are anticipated as a result of increasing temperatures, with heating demands decreasing and cooling demands increasing over time. In the future, less natural gas, electricity, and wood fuel will be used for winter heating, and our built infrastructure will need to be designed to accommodate increasing cooling demand. Currently, many commercial buildings already use energy for cooling, though residential buildings are largely cooled by night air. As cooling degree days increase along with a rise in the number of tropical nights, the ability of buildings to cool without mechanical systems will decrease, and energy use for air conditioning may increase. Long-term planning of energy infrastructure could be significantly affected by the projected major shift in heating requirements. As buildings require more energy for cooling, summer energy supply may become a challenge for our province, as BC’s energy infrastructure has been built to accommodate peak demand in winter. This could be further exacerbated if cooling demand in residential buildings increases in other regions, and if hydropower capacity is decreased due to reduced snowpack and receding glaciers that feed storage reservoirs. Seasonal and longer-term energy demands in buildings will change across the province in response to warmer temperatures. The business case for energy efficient buildings will also improve as our energy infrastructure is challenged. Installing natural and/or passive shading and green roofs on the current and future building stock could become more cost effective and could “future-proof” buildings for climate change. Transportation, Recreation, and Tourism Warmer winters and less frost may provide more opportunities for year-round active transportation (cycling and walking), and may improve safety for all road users. Additionally, as freeze-thaw cycles become more infrequent, roads may require less maintenance from winter cracking. Warmer winters may have a negative impact on local snowsport operators, possibly causing a decrease in winter tourism due to inadequate snowfall and the reduction in the number of suitable skiing days. Conversely, warmer temperatures and drier summers may benefit tourism opportunities in the summer season. Climate Projections for Metro Vancouver REPORT 41 REGIONAL IMPACTS OF CLIMATE CHANGE Summary and Recommendations This report uses current climate model outcomes to provide a “best guess” snapshot of how climate change will unfold in Metro Vancouver over the coming decades. The following projections were identified, and are worthy of attention by planners, decision makers, and infrastructure managers in the region. All models project daytime high and nighttime low temperatures to rise. While temperature can be expected to increase year round, the greatest increases will occur in the summer months. Monthly high and low temperatures show that the “new normal” for the region may be very unlike the past. Rising temperatures will lead to: hotter summer days and nights, milder winters including a considerable reduction in frost days, and a significantly reduced spring snowpack. Our region will experience a modest increase in annual precipitation by the 2050s, though the increase in precipitation will be distributed unevenly over the seasons. The largest increases will occur in the fall season, while rain will decrease significantly in the summer months. Our region can expect: stronger and more frequent extreme rainfall events, longer summer dry spells and an extension of the dry season into September, and less precipitation falling as snow in the winter months. 42 Climate Projections for Metro Vancouver REPORT These changes will have multiple impacts on our region, some of which can be accommodated through long-range planning and early adaptation efforts. Metro Vancouver will use these projections in incorporating climate change adaptation into planning cycles and ongoing activities, and will update this resource to ensure its relevance using new regionally downscaled projections after each new Intergovernmental Panel on Climate Change (IPCC) report is released (approximately every 5 to 7 years). As Metro Vancouver and member municipalities plan to adapt to climate change, early action will enable our region to best prepare for the changes ahead and increase resilience. Decision-makers need to consider the sensitivity of the systems they manage to the possible range of future climate in the region. Risk management approaches should be applied to address the uncertainty of climate risks. Vulnerability assessments may be conducted to set priorities for more detailed studies and monitoring, to understand the economic costs of climate impacts, and to inform policy, as well as planning and implementation of adaptation actions. Adaptation actions should be chosen that perform well across the range of uncertainty, to ensure robust systems. Flexibility in adaptation planning will allow the region to evolve as the future climate unfolds. APPENDIX 1 Appendix 1: RCP4.5 and RCP2.6 Tables and Figures This appendix presents climate projections for two alternate greenhouse gas emissions scenarios, RCP4.5 and RCP2.6, using the same ensemble of models described in the Methodology section. The report body presented climate projections for the RCP8.5 “business-as-usual” emissions scenario, which corresponds to a world where the rate of emissions remains similar to present day. Under RCP4.5, total emissions to the end of the century would be cut in half compared to the RCP8.5 scenario. The RCP2.6 emissions scenario assumes that the world would achieve substantial and sustained reductions in emissions starting in the present decade. For all three scenarios, atmospheric greenhouse gas concentrations and the resulting changes in climate are somewhat similar until the 2050s, but diverge considerably by the 2080s. It is worth pointing out that even under the RCP2.6 emissions scenario, our regional climate will still change compared to the past baseline, due to a continued increase in atmospheric greenhouse gas concentrations until about the 2050s. Some form of adaptation will be required regardless of socioeconomic, technological, and policy changes in coming decades. The RCP4.5 and RCP2.6 scenarios can be useful to compare relative risks for a range of possible futures. They are also useful to compare the costs and benefits of mitigation with the costs of adapting to a substantially different climate if mitigation actions are not pursued. The sections and tables in this appendix are organized and numbered to mirror the corresponding sections and tables in the main body of the report, for ease of comparison. The descriptions of each indicator are not repeated here, and tables are presented without a written explanation of the projections. Climate Projections for Metro Vancouver REPORT 43 APPENDIX 1 LIST OF TABLES Table A1: Average Daytime High Temperature...........................................................................43 Table A2: Average Nighttime Low Temperature.........................................................................43 Table A3: Total Precipitation over Seasons and Year...................................................................46 Table A6: Annual Dry Spells...........................................................................................................48 Table A7: Extreme Rainfall.............................................................................................................48 Table A8: 1-in-20 Wettest Day.......................................................................................................49 Table A9: Hot Summers Indicators................................................................................................49 Table A10: Growing-Season Length.............................................................................................50 Table A11: Growing Degree Days.................................................................................................50 Table A12: Cooling Degree Days..................................................................................................50 Table A13: Warmer Winters...........................................................................................................51 Table A14: Frost Days.....................................................................................................................51 Table A15: Heating Degree Days..................................................................................................52 LIST OF FIGURES Figure A1: Monthly Daytime High Temperature for RCP4.5.......................................................44 Figure A2: Monthly Daytime High Temperature for RCP2.6.......................................................44 Figure A3: Monthly Nighttime Low Temperature for RCP4.5.....................................................45 Figure A4: Monthly Nighttime Low Temperature for RCP2.6.....................................................45 Figure A5: Monthly Total Precipitation for RCP4.5......................................................................46 Figure A6: Monthly Total Precipitation for RCP2.6......................................................................47 44 Climate Projections for Metro Vancouver REPORT APPENDIX 1 General Climate Projections Warmer Temperatures table A1 AVERAGE DAYTIME HIGH TEMPERATURE Past (ºC) RCP4.5 RCP2.6 2050s Change (°C) 2080s Change (°C) 2050s Change (°C) 2080s Change (°C) Average (Range) Average (Range) Average (Range) Average (Range) Winter 5 1.9 (1.1 to 2.5) 2.4 (1.5 to 3.1) 1.5 (0.9 to 2.0) 1.7 (1.0 to 2.3) Spring 12 2.5 (1.5 to 3.9) 3.1 (2.1 to 4.9) 1.7 (1.1 to 2.6) 1.9 (1.1 to 2.7) Summer 21 2.7 (1.5 to 3.9) 3.3 (1.9 to 5.1) 1.9 (1.0 to 3.1) 1.6 (0.5 to 3.0) Fall 13 2.0 (0.9 to 2.7) 2.6 (1.7 to 3.4) 1.5 (0.7 to 2.1) 1.5 (0.7 to 2.1) Annual 13 2.3 (1.2 to 3.0) 2.8 (1.8 to 4.0) 1.6 (1.0 to 2.3) 1.7 (0.9 to 2.5) table A2 AVERAGE NIGHTTIME LOW TEMPERATURE Past (ºC) RCP4.5 2050s Change (°C) Average (Range) RCP2.6 2080s Change (°C) 2050s Change (°C) Average (Range) Average (Range) 2080s Change (°C) Average (Range) Winter -1 2.3 (1.6 to 3.0) 2.9 (1.8 to 3.8) 1.9 (1.3 to 2.4) 2.1 (1.5 to 2.7) Spring 3 2.3 (1.6 to 2.9) 3.0 (2.3 to 3.9) 1.8 (1.5 to 2.3) 2.0 (1.4 to 2.9) Summer 10 2.2 (1.3 to 3.3) 2.9 (1.9 to 4.4) 1.7 (1.1 to 2.7) 1.7 (1.1 to 2.7) Fall 5 2.0 (1.1 to 2.8) 2.6 (1.8 to 3.5) 1.5 (0.9 to 2.1) 1.6 (0.9 to 2.4) Annual 4 2.2 (1.4 to 2.9) 2.8 (2.0 to 3.7) 1.7 (1.4 to 2.3) 1.9 (1.3 to 2.5) Climate Projections for Metro Vancouver REPORT 45 APPENDIX 1 Seasonal Variability in Temperatures Maximum Temperature in Metro Vancouver figure A1 MONTHLY DAYTIME HIGH TEMPERATURE FOR RCP4.5 Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. Maximum Temperature in Metro Vancouver figure A2 MONTHLY DAYTIME HIGH TEMPERATURE FOR RCP2.6 Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. 46 Climate Projections for Metro Vancouver REPORT APPENDIX 1 Maximum Temperature in Metro Vancouver figure A3 MONTHLY NIGHTTIME LOW TEMPERATURE FOR RCP4.5 Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. figure A4 MONTHLY NIGHTTIME LOW TEMPERATURE FOR RCP2.6 figure A4 MONTHLY NIGHTTIME LOW TEMPERATURE FOR RCP2.6 Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. Climate Projections for Metro Vancouver REPORT 47 METHODOLOGY Wetter Winters, Drier Summers table A3 TOTAL PRECIPITATION OVER SEASONS AND YEAR RCP4.5 Past (mm) 2050s Percent Change (%) Average RCP2.6 2080s Percent Change (%) (Range) Average (Range) 2050s Percent Change (%) 2080s Percent Change (%) Average (Range) Average (Range) Fall 580 6 (-1 to 19) 15 (0 to 27) 11 (-3 to 25) 12 (2 to 28) Winter 683 9 (-2 to 22) 8 (-6 to 16) 6 (-6 to 15) 6 (1 to 11) Spring 400 7 (2 to 15) 9 (1 to 16) 8 (3 to 15) 6 (-1 to 13) Summer 206 -15 (-35 to 10) -8 (-25 to 14) -1 (-25 to 13) 1869 5 (4 to 13) 7 (0 to 13) 7 (3 to 11) Annual (-39 to 2) (0 to 11) -15 8 figure A5 MONTHLY TOTAL PRECIPITATION FOR RCP4.5 Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. 48 Climate Projections for Metro Vancouver REPORT APPENDIX 1 figure A6 MONTHLY TOTAL PRECIPITATION FOR RCP2.6 Boxes from left to right in each month indicate past, 2050s, 2080s. Further explanation of how to read the box-and-whisker plots is provided above in the Methodology section. Climate Projections for Metro Vancouver REPORT 49 APPENDIX 1 Precipitation Indicators Note: the snowpack model was not run for the RCP4.5 and RCP2.6 scenarios. Table numbering intentionally skips A4 and A5 to maintain consistency. table A6 ANNUAL DRY SPELLS RCP4.5 CLIMDEX index: CDD Past (days) Dry spell duration 2050s Percent Change (%) RCP2.6 2080s Percent Change (%) Average (Range) Average (Range) 16 (-1 to 35) 21 (6 to 34) 21 2050s Percent Change (%) Average 4 2080s Percent Change (%) (Range) Average (Range) (-11 to 18) 3 (-7 to 12) table A7 EXTREME RAINFALL RCP4.5 Climdex Index 50 Past (mm) 2050s Percent Change (%) Average (Range) RCP2.6 2080s Percent Change (%) Average (Range) 2050s Percent Change (%) Average 2080s Percent Change (%) (Range) Average (Range) One-day maximum precipitation Rx1day 69 15 (7 to 24) 20 (12 to 30) 12 (1 to 22) 12 (1 to 21) Five-day maximum precipitation Rx5day 159 10 (2 to 20) 15 (4 to 26) 10 (1 to 18) 9 (-2 to 20) 95th percentile wettest days precipitation R95pTOT 398 29 (12 to 56) 43 (25 to 57) 29 (5 to 49) 28 (10 to 55) 99th percentile wettest days precipitation R99pTOT 122 45 (15 to 62) 79 (43 to 111) 47 (12 to 82) 49 (15 to 96) Climate Projections for Metro Vancouver REPORT APPENDIX 1 table A8 1-IN-20 WETTEST DAY RCP4.5 Past (mm) 2050s Percent Change (%) RCP2.6 2080s Percent Change (%) 2050s Percent Change (%) Average (Range) Average (Range) Average (Range) 2080s Percent Change (%) Average (Range) Region 105 31 (3 to 45) 32 (17 to 51) 20 (7 to 31) 16 (-3 to 35) Low elevations 89 28 (-2 to 47) 34 (12 to 55) 20 (11 to 28) 14 (-7 to 33) High elevations 121 25 (9 to 39) 29 (16 to 49) 16 (4 to 30) 11 (-5 to 36) Summer Temperature Indicators Note: the Heat Days indicator was not computed for the other emissions scenarios. table A9 HOT SUMMERS INDICATORS CLIMDEX index RCP4.5 Past 2050s Change Average (Range) RCP2.6 2080s Change Average (Range) 2050s Change Average (Range) 2080s Change Average (Range) Summer days (# of days >25°C) SU 22 31 (3 to 45) 32 (17 to 51) 20 (7 to 31) 16 (-3 to 35) Tropical nights (# of nights >20°C) TR 0 28 (-2 to 47) 34 (12 to 55) 20 (11 to 28) 14 (-7 to 33) 1-yr TXx 31 25 (9 to 39) 29 (16 to 49) 16 (4 to 30) 11 (-5 to 36) 34 3.3 (1.6 to 4.8) 4.1 (2.4 to 5.6) 2.1 (0.4 to 3.8) 2.5 (0.6 to 4.5) Hottest day (°C) 1-in-20 hottest day (°C) Climate Projections for Metro Vancouver REPORT 51 APPENDIX 1 table A10 GROWING SEASON LENGTH RCP4.5 Climdex index: GSL Past (days) RCP2.6 2050s Change (days) 2080s Change (days) Average (Range) Average (Range) 2050s Change (days) 2080s Change (days) Average (Range) Average (Range) Region 252 42 (29 to 50) 52 (41 to 61) 33 (27 to 41) 37 (28 to 45) Low elevations 301 38 (30 to 43) 43 (36 to 50) 33 (27 to 38) 36 (31 to 42) High elevations 217 49 (24 to 66) 65 (49 to 81) 38 (27 to 53) 42 (26 to 54) table A11 GROWING DEGREE DAYS RCP4.5 Past (degree days) RCP4.5 2050s Change (degree days) Average 2080s Change (degree days) 2050s Change (degree days) 2080s Change (degree days) (Range) Average (Range) Average (Range) Average (Range) Region 1738 606 (331 to 826) 785 (516 to 1061) 449 (304 to 648) 456 (275 to 662) Low elevations 2122 681 (393 to 919) 888 (600 to 1179) 511 (364 to 711) 535 (341 to 756) High elevations 1467 557 (294 to 758) 722 (465 to 997) 408 (269 to 617) 410 (234 to 621) table A12 COOLING DEGREE DAYS Past (degree days) 52 RCP4.5 2050s Change (degree days) Average (Range) RCP2.6 2080s Change (degree days) Average (Range) 2050s Change (degree days) Average (Range) 2080s Change (degree days) Average (Range) Region 1738 112 (46 to 170) 160 (77 to 247) 75 (35 to 124) 67 (28 to 122) Low elevations 2122 146 (63 to 221) 211 (106 to 326) 97 (46 to 158) 92 (39 to 165) High elevations 1467 83 (33 to 131) 119 (54 to 185) 56 (25 to 96) 48 (20 to 90) Climate Projections for Metro Vancouver REPORT APPENDIX 1 Winter Temperature Indicators table A13 WARMER WINTERS INDICATORS RCP4.5 CLIMDEX index Past (°C) 2050s Change (°C) RCP2.6 2050s Change (°C) 2080s Change (°C) Average (Range) Average (Range) Average 2080s Change (°C) (Range) Average (Range) Warmest winter day TXx 12 2.1 (0.7 to 3.1) 3.0 (1.7 to 4.8) 1.3 (0.5 to 2) 1.9 (0.5 to 2.9) Coldest winter night TNn -13 4.1 (3 to 5.7) 4.7 (3.4 to 6.4) 3.1 (1.8 to 4.7) 3.5 (2 to 5.1) -20 2.9 (-0.8 to 5.4) 4.1 (2.3 to 6.3) 1.9 (-0.4 to 4.2) 2.6 (1 to 5.1) 1-in-20 coldest nighttime low table A14 FROST DAYS RCP4.5 CLIMDEX index: FD Past (days) 2050s Change (days) Average (Range) RCP2.6 2080s Change (days) Average (Range) 2050s Change (days) Average 2080s Change (days) (Range) Average (Range) Region 79 -39 (-45 to -27) -46 (-55 to -36) -33 (-38 to -26) -36 (-42 to -26) Low elevations 39 -25 (-28 to -19) -28 (-31 to -23) -22 (-26 to -16) -24 (-29 to -17) High elevations 92 -48 (-58 to -34) -58 (-69 to -44) -41 (-47 to -33) -45 (-55 to -32) Climate Projections for Metro Vancouver REPORT 53 APPENDIX 1 table A15 ICE DAYS RCP4.5 CLIMDEX index: ID Past (days) RCP2.6 2050s Change (days) 2080s Change (days) Average (Range) Average (Range) 2050s Change (days) 2080s Change (days) Average (Range) Average (Range) Region 12 -7 (-9 to -5) -8 (-10 to -6) -6 (-8 to -4) -6 (-8 to -3) Low elevations 4 -2 (-3 to -1) -3 (-4 to -1) -2 (-3 to -1) -2 (-3 to -1) High elevations 13 -8 (-10 to -5) -9 (-11 to -6) -6 (-9 to -4) -7 (-10 to -4) table A16 HEATING DEGREE DAYS Past (degree days) 54 RCP4.5 2050s Change (degree days) Average (Range) RCP2.6 2080s Change (degree days) Average (Range) 2050s Change (degree days) Average 2080s Change (degree days) (Range) Average (Range) Region 3489 -701 (-870 to -421) -870 (-1075 to -621) -543 (-703 to -407) -577 (-769 to -359) Low elevations 2865 -651 (-795 to -404) -810 (-998 to -588) -509 (-654 to -394) -550 (-736 to -351) High elevations 3834 -730 (-916 to -436) -909 (-1134 to -647) -563 (-736 to -420) -595 (-797 to -373) Climate Projections for Metro Vancouver REPORT APPENDIX 2 Appendix 2: RCP8.5 Supplementary Maps This appendix presents the regionally downscaled model output for RCP8.5 in the form of maps for select indicators described in the report. Maps are presented here only when they show sufficient geographic variation to add valuable information to the regional averages presented in tables. For many indicators, either the values or the projected changes in values are quite uniform across the region. In these cases, maps that do not add spatial information have been omitted. Maps that were included in the report body are not repeated in this Appendix. Different types of maps are presented for each selected indicator to add the most meaning to the interpretation. The types of maps include: Past: shows the indicator values averaged over the 30-year baseline period (1971–2000) Future: shows the projected value of the indicator for the RCP8.5 emissions scenario for the 2050s (averaged over the 30-year period 2041–2070) Anomalies: shows the difference in values between the future projections and the past baseline, in the units of the indicator (i.e., degrees Celsius, millimetres of precipitation, centimetres of snowpack, number of days, or degree days). Positive values indicate an increase from the past to the future. Climate Projections for Metro Vancouver REPORT 55 APPENDIX 2 LIST OF FIGURES Figure A7: Winter Precipitation – Past..........................................................................................57 Figure A8: Winter Precipitation – Future (2050s).........................................................................57 Figure A9: Spring Precipitation – Past..........................................................................................58 Figure A10: Spring Precipitation – Future (2050s)........................................................................58 Figure A11: Summer Precipitation – Past.....................................................................................59 Figure A12: Summer Precipitation – Future (2050s).....................................................................59 Figure A13: 1-in-20 Wettest Day – Anomalies..............................................................................60 Figure A14: Summer Average Daytime High Temperature – Past.............................................61 Figure A15: Summer Average Daytime High Temperature – Future (2050s).............................61 Figure A16: Summer Days – Past..................................................................................................62 Figure A17: Summer Days – Anomalies........................................................................................62 Figure A18: Tropical Nights – Past................................................................................................63 Figure A19: Tropical Nights – Future (2050s)................................................................................63 Figure A20: Hottest Day – Past......................................................................................................64 Figure A21: Hottest Day – Future (2050s).....................................................................................64 Figure A22: 1-in-20 Hottest Day – Past.........................................................................................65 Figure A23: 1-in-20 Hottest Day – Future (2050s)........................................................................65 Figure A24: Growing Season Length – Past.................................................................................66 Figure A25: Growing Season Length – Future (2050s)................................................................66 Figure A26: Spring Nighttime Low Temperature – Past..............................................................67 Figure A27: Spring Nighttime Low Temperature – Future (2050s).............................................67 Figure A28: Coldest Night – Past..................................................................................................68 Figure A29: Coldest Night – Future (2050s).................................................................................68 Figure A30: 1-in-20 Coldest Night – Past.....................................................................................69 Figure A31: 1-in-20 Coldest Night – Anomalies..........................................................................69 Figure A32: Ice Days – Past............................................................................................................70 Figure A33: Ice Days – Future (2050s)...........................................................................................70 56 Climate Projections for Metro Vancouver REPORT Precipitation indicators APPENDIX 2 Figure A7. Winter Precipitation - Past 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) Precipitation Indicators 3 -123.5 -123.0 -122.5-122.0 Figure A8. Winter Precipitation – Future (2050s) LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A7: WINTER PRECIPITATION – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A8: WINTER PRECIPITATION – FUTURE (2050s) Figure A9. Spring Precipitation – Past. Climate Projections for Metro Vancouver REPORT 57 APPENDIX 2 49.0 49.2 LATITUDE (ºN) 49.4 49.649.8 4 -123.5 -123.0 -122.5-122.0 Figure A10. Spring Precipitation – Future (2050s) LONGITUDE (ºN) FIGURE A9: SPRING PRECIPITATION – PAST 49.0 49.2 LATITUDE (ºN) 49.4 49.649.8 Figure A10. Spring Precipitation – Future (2050s) -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A10: SPRING PRECIPITATION – FUTURE (2050s) 58 Climate Projections for Metro Vancouver REPORT APPENDIX 2 Figure A11. Summer Precipitation – Past 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) Note: scale changes with each season 6 -123.5 -123.0 -122.5-122.0 Figure A12. Summer Precipitation – Future (2050s) LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A11: SUMMER PRECIPITATION – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A12: SUMMER PRECIPITATION – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 59 Figure A13. 1-in-20 Wettest Day anomalies. 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) APPENDIX 2 of past and future 1-in-20 wettest day precipitation are provided in the report body. Note: maps This map shows the change between past and future values. -123.5-123.0-122.5-122.0 LONGITUDE (ºN) FIGURE A13: 1-IN-20 WETTEST DAY ANOMALIES 60 Climate Projections for Metro Vancouver REPORT Summer temperature indicators 49.4 49.649.8 APPENDIX 2 49.2 49.0 LATITUDE (ºN) Figure A14. Summer Average Daytime High Temperature - Past 9 -123.5-123.0-122.5-122.0 LONGITUDE (ºN) FIGURE A14: SUMMER AVERAGE DAYTIME HIGH TEMPERATURE – PAST 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) Figure A15. Summer Average Daytime High Temperature – Future (2050s) -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A15: SUMMER AVERAGE DAYTIME HIGH TEMPERATURE – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 61 Figure A16. Summer Days – Past Note: map of summer days future projections (2050s) is presented in report body. 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) APPENDIX 2 11 -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) Figure A17. Summer Days – Anomalies 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A16: SUMMER DAYS – PAST -123.5-123.0-122.5-122.0 LONGITUDE (ºN) FIGURE A17: SUMMER DAYS – ANOMALIES 62 Climate Projections for Metro Vancouver REPORT 49.2 49.4 49.649.8 APPENDIX 2 49.0 LATITUDE (ºN) Figure A18. Tropical Nights - Past 13 -123.5-123.0-122.5-122.0 LONGITUDE (ºN) Figure A19. Tropical Nights – Future (2050s) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A18: TROPICAL NIGHTS – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A19: TROPICAL NIGHTS – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 63 Figure A20. Hottest Day – Past 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) APPENDIX 2 15 -123.5-123.0-122.5-122.0 LONGITUDE (ºN) Figure A21. Hottest Day – Future (2050s) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A20: HOTTEST DAY – PAST -123.5-123.0-122.5-122.0 LONGITUDE (ºN) FIGURE A21: HOTTEST DAY – FUTURE (2050s) 64 Climate Projections for Metro Vancouver REPORT 49.4 49.649.8 APPENDIX 2 49.2 49.0 LATITUDE (ºN) Figure A22. 1-in-20 Hottest Day – Past 17 -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) Figure A23. 1-in-20 Hottest Day – Future (2050s) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A22: 1-IN-20 HOTTEST DAY– PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A23: 1-IN-20 HOTTEST DAY– FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 65 Figure A24. Growing Season Length – Past 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) APPENDIX 2 19 -123.5 -123.0 -122.5-122.0 (ºN) Figure A25. Growing Season Length –LONGITUDE Future (2050s) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A24: GROWING SEASON LENGTH – PAST -123.5-123.0-122.5-122.0 LONGITUDE (ºN) FIGURE A25: GROWING SEASON LENGTH – FUTURE (2050s) 66 Climate Projections for Metro Vancouver REPORT Winter temperature indicators APPENDIX 2 Figure A26. Spring Nighttime Low Temperature - Past 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) Winter Temperature Indicators 21 -123.5 -123.0 Figure A27. Spring Nighttime Low Temperature -122.5-122.0 – Future (2050s) LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A26: SPRING NIGHTTIME LOW TEMPERATURE – PAST -123.5-123.0-122.5-122.0 LONGITUDE (ºN) FIGURE A27: SPRING NIGHTTIME LOW TEMPERATURE – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT 67 Figure A28. Coldest Night – Past 49.4 49.649.8 49.2 23 49.0 LATITUDE (ºN) APPENDIX 2 -123.5 Figure A29. Coldest Night -123.0 – Future (2050s) -122.5-122.0 LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A28: COLDEST NIGHT– PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A29: COLDEST NIGHT – FUTURE (2050s) 68 Climate Projections for Metro Vancouver REPORT 49.4 49.649.8 APPENDIX 2 49.2 49.0 LATITUDE (ºN) Figure A30. 1-in-20 Coldest Night – Past 25 -123.5 -123.0 Figure A31. 1-in-20 Coldest Night – Anomalies -122.5-122.0 LONGITUDE (ºN) 49.4 49.649.8 49.2 49.0 LATITUDE (ºN) FIGURE A30: 1-IN-20 COLDEST NIGHT– PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A31: 1-IN-20 COLDEST NIGHT – ANOMALIES Climate Projections for Metro Vancouver REPORT 69 27 APPENDIX 2 49.0 49.0 49.2 LATITUDE (ºN) LATITUDE (ºN) 49.4 49.649.8 Figure A32: Ice Days – Past 28 Figure A33: Ice Days – Future -123.5 -123.0(2050s) 70 -122.5-122.0 LONGITUDE (ºN) 49.2 49.4 49.649.8 FIGURE A32: ICE DAYS – PAST -123.5 -123.0 -122.5-122.0 LONGITUDE (ºN) FIGURE A33: ICE DAYS – FUTURE (2050s) Climate Projections for Metro Vancouver REPORT June 2016 Climate Projections for Metro Vancouver REPORT 71 Notes 72 Climate Projections for Metro Vancouver REPORT Climate Projections for Metro Vancouver REPORT 73

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